# plot

## Description

## Examples

### Radar Signal Backscattered by Bicyclist

Compute the backscattered radar signal from a bicyclist moving along the *x*-axis at 5 m/s away from a radar. Assume that the radar is located at the origin. The radar transmits an LFM signal at 24 GHz with a 300 MHz bandwidth. A signal is reflected at the moment the bicyclist starts to move and then one second later.

**Initialize Bicyclist, Waveform, and Propagation Channel Objects**

Initialize the `backscatterBicyclist`

, `phased.LinearFMWaveform`

, and `phased.FreeSpace`

objects. Assume a 300 MHz sampling frequency. The initial position of the bicyclist lies on the *x*-axis 30 meters from the radar.

bw = 300e6; fs = bw; fc = 24e9; radarpos = [0;0;0]; bpos = [30;0;0]; bicyclist = backscatterBicyclist( ... 'OperatingFrequency',fc,'NumWheelSpokes',15, ... 'InitialPosition',bpos,'Speed',5.0, ... 'InitialHeading',0.0); lfmwav = phased.LinearFMWaveform( ... 'SampleRate',fs, ... 'SweepBandwidth',bw); sig = lfmwav(); chan = phased.FreeSpace( ... 'OperatingFrequency',fc, ... 'SampleRate',fs, ... 'TwoWayPropagation',true);

**Plot Initial Bicyclist Position**

Using the `move`

object function, obtain the initial scatterer positions, velocities and the orientation of the bicyclist. Plot the initial position of the bicyclist. The `dt`

argument of the `move`

object function determines that the next call to `move`

returns the bicyclist state of motion `dt`

seconds later.

dt = 1.0; [bpos,bvel,bax] = move(bicyclist,dt,0); plot(bicyclist)

**Obtain First Reflected Signal**

Propagate the signal to all scatterers and obtain the cumulative reflected return signal.

N = getNumScatterers(bicyclist); sigtrns = chan(repmat(sig,1,N),radarpos,bpos,[0;0;0],bvel); [rngs,ang] = rangeangle(radarpos,bpos,bax); y0 = reflect(bicyclist,sigtrns,ang);

**Plot Bicyclist Position After Position Update**

After the bicyclist has moved, obtain the scatterer positions and velocities and then move the bicycle along its trajectory for another second.

[bpos,bvel,bax] = move(bicyclist,dt,0); plot(bicyclist)

**Obtain Second Reflected Signal**

Propagate the signal to all scatterers at their new positions and obtain the cumulative reflected return signal.

sigtrns = chan(repmat(sig,1,N),radarpos,bpos,[0;0;0],bvel); [~,ang] = rangeangle(radarpos,bpos,bax); y1 = reflect(bicyclist,sigtrns,ang);

**Match Filter Reflected Signals**

Match filter the reflected signals and plot them together.

mfsig = getMatchedFilter(lfmwav); nsamp = length(mfsig); mf = phased.MatchedFilter('Coefficients',mfsig); ymf = mf([y0 y1]); fdelay = (nsamp-1)/fs; t = (0:size(ymf,1)-1)/fs - fdelay; c = physconst('LightSpeed'); plot(c*t/2,mag2db(abs(ymf))) ylim([-200 -50]) xlabel('Range (m)') ylabel('Magnitude (dB)') ax = axis; axis([0,100,ax(3),ax(4)]) grid legend('First pulse','Second pulse')

Compute the difference in range between the maxima of the two pulses.

[maxy,idx] = max(abs(ymf)); dpeaks = t(1,idx(2)) - t(1,idx(1)); drng = c*dpeaks/2

drng = 4.9965

The range difference is 5 m, as expected given the bicyclist speed.

## Input Arguments

`bicyclist`

— Bicyclist target

`backscatterBicyclist`

object

Bicyclist, specified as a `backscatterBicyclist`

object.

`ax`

— Plot axes

axes handle

Plot axes, specified as an axes handle.

**Data Types: **`double`

## Output Arguments

`fhndl`

— figure handle

figure handle

Figure handle of plot window.

## Version History

**Introduced in R2019b**

## See Also

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